Temperature Dependence of Triton X-100 Micelle Size and Hydration

Abstract

Quasi-elastic light scattering spectroscopy was used to measure the mutual diffusion coefficient, D,, of Triton X-100 micelles in aqueous solution and the translational diffusion coefficient, D,, of mesoscopic probes in the same solutions. We apply conventional hydrodynamic treatments of diffision under the assumption that Triton X-100 minimal micelles are adequately represented as hard spheres. Dm and D, measured at a series of surfactant concentrations are used to infer the micelle radius, am, aggregation number, N , and degree of hydration, 6, for temperatures 10 5 T 5 50 "C. As T is increased toward the cloud point, am and N increase, the increase in N being especially dramatic above 40 "C, 6 at first increases but then tends to saturate with increasing T.